Process for preparing aromatic mercaptans



Patented Ma. 26, 1929.

UNITED STATES PATENT OFFICE.

ERWIN HOFFA AND IPAUL-JORG, OF HOCHST-ON-THE-MAIN, GERMANY, ASSIGNORS TO GRASSELLI DYE-STUFF CORPORATION, OF NEW YORK, N. Y., A. CORPORATION OF DELAWARE.

PROCESS FOR PREPARING AROMATIC MEBCAPTAN S.

No Drawing. Application filed. September 21, 1927, Serial No. 221,135, and in Germany October 18, 1926.

Our present invention relates to a new method of preparing aromatic mercaptans. Hitherto no process has been known by which it is possible to prepare mercaptans of the general formula: R.SH (wherein R means a non-substituted or substituted benzeneor naphthalene residue) with a yield adequate for technical purposes, by causing diazoaryles to 'act upon metal disulfides and subjecting to reduction. the aryldisulfides thus produced having the general formula:

R.S.S.R; there being excluded from the said diazoaryles only those which contain a solobilizing group, for instance the carboxyl group.

Now we have found that yields-which are adequate for technical purposes can be obtained also from diazoaryles containing no solubilizing group, by causing the dlazoaryles to act upon higher sulfurized metals instead of metal disulfides and subjecting the products of the reaction toreduction. The metal sulfides in question must contain a higher .percentage, pf sulfur than corresponds to the formula Me s wherein .Me

stands for one equivalent of a metal, for instance more than Na s or CaS The action of the dissolved diazo compounds upon the metal sulfides advantageously takes place at temperatures not considerably below 60 0., since explosive diazo sulfides can be formed at lower temperatures, the upper limit of temperature is the boiling point of the aqueous sulfide solution, i. e., about 100C. The addition of an alkali, for instance a carbonate, bicarbonate, alkali silicate, or of catalytically acting metals or metal compounds (copper, copper j salts) very often causes an increase of the yields.

The fol-lowingexamples serve to illustrate our invention, but they are not-intended to limit it thereto, the parts, beingparts by weight: I v (1). 56,4 parts of 5-ch'lor-2-amino-1 methylbenzene are mixed and stirred with 120 parts by volume of concentrated hydrochloric acid of specific gravity 1.19 and 400 parts of water and the mixture isthen diazotized in the usual manner at 05 C. with a concentrated aqueous solution'of 28 parts of sodium nitrite. The diazo solution is mixed at 0 C.5 with a caustic soda solution until its reaction towards Congo red has disappeared and is then run, while stirring, into the whole is stirred for another 12 hours.

The oil which, aftercooling, is separated .can be reduced in the usual manner so as to yleld mercaptan of the following formula:

The latter may be converted without any previous purification into the corresponding arylthioglycollic acid by the action of chloroacetic acid. o

(2). 56,4 parts of 5 chlor 2 amino 1 methylbenzene are diazotized inthe manner indicated in Exam le 1. The diazo solution, after being neutra ized by means of a caustic soda solution, is run, while stirring it, into a polysulfide solution having a. temperature of about C. to about C. and being prepared by boiling for 3 hours on the reflux condenser 28.8 parts of commercial calcium sulfide, 60 parts of sulfur and 400 parts of water and then filtering the mass. The resulting mass is then worked up as indicated in Example 1.

(g). A diazo solution, prepared according to xample 1 from 56,4 parts of 5-chlor-2- amino-l-m'ethylbenzene and neutralized by means ofa caustic soda solution, is run at 60 C.70 G. into a polysulfide solution obtained from 96 parts of sodium sulfide cryst, 48 parts of sulfur and 400 parts of water and to which 30 parts of sodium carbonate and a concentrated solution of one part of copper .sulfatehave been added. The resulting product is then further worked up as indicated in Example 1. 'In the following claims we understand by the term copper-catalyst metallic copper as well as copper compounds.

We claim: 1. The process for preparin aromatic merca tans of the eneral formu a:R-SH

.wherem stands or a substituted or nonsubstituted aromatic residue, which consists in causing any aqueous diazoaryl solution and a metal compound containing more sulfur than corresponds to the formula Me s wherein Me stands for one equivalent of a metal to act upon each other at a temperature between 60C. and 100 C. and reducing the reaction products thus obtained.

2. The process for preparing aromatic mercaptans of the general formula: R-SH wherein R stands for a substituted or nonsubstituted aromatic residue, which consists in causing any aqueous diazoaryl solution and a metal compound containing more sulfur than corresponds to the formula Me s wherein Me stands for one equivalent of a metal to act upon each other at a temperature between 65 C. and 70 C. and reducing the a reaction products thus obtained. a

3. The process for preparing aromatic mercaptans of the general formula: RSH wherein It stands for a substituted or nonsubstituted aromatic residue, which consists i metal with the addition of an alkali to act I products thus obtained.

in causing any aqueous diazoaryl solution and a metal compound containing more sul fur than corresponds to the formula Me S wherein Me stands for one equivalent of 3.

upon each other at a temperaturev between 60 C. and 100 C. and reducing the reaction 4. The process for preparing aromatic mercaptans of the general formula: RSH wherein R,stands for a substituted or nonsubstituted aromatic residue, which consists in causing any aqueous diazoaryl solution and a metal compound containing more sulfur than corresponds to the formula Me S wherein Me stands for one equivalent of a metal with the addition of an alkali and a copper catalyst to act upon each other at a temperaturebetween 60 C. and 100 C. and

reducing the reaction products thus obtained.

5. The process for pre arin aromatic mercaptans of the general ormu a: R--SH wherein R stands for a substituted or nonsubstituted aromatic residue, which consists in causing any aqueous diazoaryl solution and Na S to act upon each other at a temperature between 60 C. and 100 C. and reducing the reaction products thus obtained.

6. The process for preparing aromatic mercaptans of the general formula: RSH wherein R stands for a-substituted or nonsubstituted aromatic residue, which consists 1 in causing any aqueous diazoaryl solution and 1 SH I 5 3 4 O which consists in causing an aqueous solution of the diazotized 5 chlor 2 amino 1 methylbenzene and Na s g to act-upon each other atatemperature between 60 C and 100 C. and reducing the reaction products thus obtained.

I 10. The process for preparing a. mercaptan of the'following formula: V

5 3 c {V which consists in causing an aqueous solution of the diazotized 5-chlor-2-toluidine and Na S to act upon each other at a temperature between C. and C. and reducing the reaction products thus obtained.

11. The process for preparing a mercaptan of the following formula:

CHa

which consists in causing an aqueous solution of the 'diazotized 5 chlor-2-toluidine and N a S with the addition of an alkali to act upon each other at a temperature between 60 C. and 100 C. and reducing the reaction products thus obtained.

- 12. The process for preparing a mercaptan of the following formula:

01 which consists in causing an aqueous solution of the diazotized 5-chlor-2-toluidine and N84S4K with the addition of an alkali and a copper catalyst to act upon each other at which consists in causing an aqueous solution a temperature between 60 C. and 100 C. of the diazotized 5-ch1or-2-toluidine and and reducing the reaction products thus ob- Na S with the addition of sodium carbon- 15 tained. ate and copper sulfate to act upon each other 13. The process for preparing a mercaptan at a temperature between 65 C. and 70 C.

of the following formula: v and reducing the reaction products thus obtained.

v In testimony whereof, We affix our signa- 20 II tures.

6 2 if 4 ERWVIN HOFFA. o1 PAUL J ORG. 

